The present invention relates to an apparatus for lifting a heavy load and transporting it over an obstruction and particularly, but not exclusively, for the rapid transport of mandrels in a continuous rolling mill for the production of tubes without welding.
During the operation of a continuous rolling mill, in which tubes are made by rolling intermediate forgings carried on respective mandrels, the mandrels are recovered from the rolling operation and are returned to the inlet to the mill along a so-called mandrel circulation route. This route traverses successive stations during which operations such as cooling and lubrication of the mandrels are carried out and, in most cases, terminates at a take-up station during which the mandrels, which are ready to be re-used, are fed at predetermined, regular time intervals. The take-up station is normally located to one side of an input roller bed of the rolling mill, the mandrels being arranged with their axes parallel to the rolling axis, and from here they are transferred to a pre-insertion table, usually at the other side of the input roller bed, where they are inserted into respective intermediate forgings.
During the transfer from the take-up station to the pre-insertion table, the mandrels are moved perpendicular to their axes and must be lifted over the roller bed and any other obstructing part of the rolling mill. The known apparatus for effecting this transfer has many disadvantages, one of which is the lengthy time needed for completion of the transfer. A further disadvantage is that most known apparatus employ cables for lifting the mandrels and these may allow pendular swinging of the mandrels during transfer.
The object of the present invention is to provide apparatus for lifting and transporting heavy objects, particularly for lifting and transporting mandrels in a continuous rolling mill, which can effect the transfer of a mandrel from the take-up station, over the input roller bed and onto the pre-insertion table more rapidly than the known apparatus and with less risk of pendular swinging of the mandrel.